SQL仅返回另一个表中存在的ID

Question

How can I return the check_type_dim_id 's from the Check_Type_Dimension table that exist exclusively in the Check_Type_Master table?

I should only be returned 5 results but I'm getting 6 because of trying to join on the names:

WHERE EXISTS
(SELECT check_type_id FROM check_type_master CTM WHERE 
 CTM.check_type_name = CTD.check_type_name)

The trouble is, the check_type_dim_id is an auditing table and can have duplicate names.

Table: Check_Type_Dimension contains the following info:

Table Check_Type_Master contains the following info:

Answer 1

SELECT CTM.id
FROM check_type_master CTM 
JOIN Check_Type_Dimension CTD 
    ON CTM.check_type_name= CTD.check_type_name AND  CTM.check_type_id= CTD.check_type_id

Answer 2

If I understood correctly, that should solve your problem:

SELECT check_type_dim_id FROM Check_Type_Dimension
WHERE check_type_dim_id IN (SELECT check_type_dim_id FROM Check_Type_Master)

Generally, you can use IN operator with the subquery, to restrict some column to the set, returned by the subquery (it has to be one-column table).

Answer 3

You should link the 2 tables in the EXISTS both on id & name.

Because you when the Dimension table has 2 different id's with the same name ("Member Charge") then your query would give extra results.

Example:

select check_type_dim_id
from Check_Type_Dimension CTD 
where exists (
   select 1
   from Check_Type_Master CTM
   where CTM.check_type_id = CTD.check_type_id
     and CTM.check_type_name = CTD.check_type_name
);